Known in the present state of the art is a device for measurement of arterial blood pressure (cf. SU, A, No. 651,786), comprising a compression cuff with a manometer and a cardiac sounds sensor interposed between the compression cuff and the patient's body surface below the cuff axis transverse with respect to the direction of motion of the pulse wave.
The cardiac sounds sensor comprises a casing, a piezoelectric crystal plate secured in the casing, and a contact element made fast at the centre of the piezoelectric crystal plate. Sound vibrations arising in body tissues in response to a pressure change in the compression cuff caused by propagation of the pulse waves, are picked up, through the contact element, by the piezoelectric crystal plate and are converted into electric signals, which are then applied to a recorder.
Disadvantages of the above mentioned device are that the cardiac sounds sensor features too low accuracy of measurement of arterial blood pressure due to the fact that it responses not only to a useful signal but also to false or spurious signals caused by any extraneous acoustic noice, pressure fluctuations in the cuff, or muscular contrations. In addition, the known sensor is inapplicable for measuring the arterial blood pressure in infants or preschool children, since the useful signal in them is too weak and cannot therefore be discriminated by the cardiac sounds sensor against a background of acoustic noise.
One more prior-art device for measurement of arterial blood pressure is known (cf. SU, A, No. 895,405) to comprise a compression cuff, a manometer, a pulse wave sensor interposed between the compression cuff and the patient's body surface below the cuff axis transverse with respect to the direction of the pulse wave propagation, and connected to a recorder.
The pulse wave sensor comprises a casing, a piezoelectric crystal plate one of whose working surfaces carries a first elastic current-conducting layer, while the other working surface of the piezoelectric crystal plate carries a second elastic current-conducting layer, which piezoelectric crystal plate is secured in the casing and is connected to a contact element.
When the pulse wave is propagated under the sensor, the contact element performs angular oscillations which are converted by the piezoelectric crystal plate into an electric signal proportional to the amplitude of the aforesaid oscillations, which signal is then delivered to the recorder.
Disadvantage of the known device for measurement of arterial blood pressure consists in that the pulse wave sensor has a casing whose interaction with the compression cuff and the patient's body might cause a noise or interfering signal, thus affecting adversely the accuracy of the arterial blood pressure measurement. Moreover, such a sensor features, as a rule, rather great dimensions which hinders its application for measure arterial blood pressure in infants or preschool children.